2000 540i E39 iDrive failed

This particular E39 belonged to my father-in-law. When he passed away in 2004, the car was garaged for a decade. It was in good condition when we started it up again in 2013, though shortly after the iDrive failed.

I haven't seen an exact description in any similar threads on the forum. The sound system actually does work - it'll play CDs or the radio, though after a few minutes (3-7) it will cut the sound even though the system still appears to be on. Turning it off and on again makes the sound work again.

The iDrive display (it's the 4:3 version) just shows static and some random lines across the screen. This obviously makes it challenging to use the radio, for instance, since I don't know what channel I'm on.

I took it to my local independent shop and they quoted me about $1800 for a refurbished replacement - mostly to find a donor iDrive. I'd like to try hooking up a Raspberry Pi with a PiBUS board, but something tells me that the screen problem will prevent that from working too.

Has anyone else overcome a similar problem, or know if the Raspberry Pi solution would be an effective workaround? I'm competent enough with cars and electronics to try some tinkering myself, but I don't want to go in totally blind. Any advice will be appreciated.